The present invention concerns a connection cable between a plurality of devices, an audio recording or reproduction system, realized with copper, silver, gold and silk or cotton dielectric wires, with the possibility of calibrating said cable, and with contact devices or connectors.
It is well known that an audio amplification system consistsxe2x80x94in a schemexe2x80x94of a signal source, of one or more amplification phases and of electroacoustic transducers. The many devices may all be contained in one single unit, called integrated system, or also in different containers connected with each other by suitable cables.
Generally, an audio system may consist of:
an audio source;
a converter for transforming the digital signal into an analogic one;
a pre-amplifier;
a power amplifier and a loudspeaker system.
All these devices are connected between each other by suitable electric cables, usually different, because the kind of electric signal is different in amplitude and electric power according to the connection.
Even if said connection is very simple, experience shows that the influence of the cables onto the quality of the. reproduced signal is determining, and that the connection contact between the devices, realized with a connector generally of the RCA-type, is very important.
Said contact is influenced in a determining manner by the employed material, which produces not only electric effects onto the reproduced signal, but influences the quality and the tone-colour of the reproduced sound.
In fact, the connection cable and the kind of contact influence:
the tone-colour of the signal;
the spatial reconstruction of the audio message;
the loss of informations;
the focusing of the sound sources;
the dynamic;
the audibility of the sound event;
the naturalness of the reproduced sound.
The variation determined in the signal by the cable, which from now on will be considered as comprising the contact connector, is such that it may be considered a decay of the reproduced signal with respect to the original event, or an altered signal due to the connection cables.
For the purpose of optimizing the cables and for reducing their influence on the signal to a minimum, specialized cables are known to the art, according to the kind of signal, which may be devided in:
digital cables,
signal cables,
speaker cables.
The realization techniques of the cables are different according to the kind of signal they will transmit.
Considering first the digital and signal cables, usually the best electric conductors are used, like silver, gold, copper and, for the dielectric ones, the most sophisticated materials, as the currents as well as the tensions used are very small and the lengths very short.
A particular study has always been made on the geometry of the conductors, with the aim of reducing the influences of the external electric fields and of the ones generated by the same signal currents.
In fact, experience teaches that changing the arrangement of the wires and the kind of screening, different acoustic results are obtained. In fact, the screening is very important; the conventional coaxial cable has proved not to be the best system for the transmission of the audio signal, even if it offers a perfect protection from external inconveniences.
The present invention came out from the experimental verification that a screening made on signal wires and another screening made on earth wires, return signal, determine a better reproduction of the sound; a further increase is obtained by further screening the two coaxial cables obtained by means of the connection of the external screen to earth.
As already mentioned, the material of the connector also influences the reproduced sound; the experiments performed in view of the present invention have shown that the pure copper connector supplies the best transmission of the audio signal in acoustic terms, as it has no particular colours.
The materials used up to nowxe2x80x94usually brass or alloys containing also brassxe2x80x94considerably alter the reproduced sound. The realization of pure copper connectors is linked to problems, as said metal is not elastic and this feature makes a safe contact very difficult in time, because the material permanently loses its shape.
According to the present invention, the problem has been solved exploiting the elasticity of a spring or of an elastic support like a small rubber pipe, wrapped around the connector""s body, so as to form the elastic part of the same. Now the copper will be galvanized with successive layers of suitable metals for avoiding the oxidation of the surface layer. Of course, also other means may be applied for bringing elasticity.
Experiments with connectors out of alloy copper have brought lower results.
It is important to underline how the influences of the single components get added in the realization of the cable, having thus a considerable overall influence onto the reproduced audio signal. Therefore, the complexity of the system has allowed to realize rather different cables: in fact, the art shows cables with the most sophisticated geometries, with different conductor materials and with the most different dielectrics.
It is the aim of the present invention to realize connection cables so as to obtaine the best electroacoustic response, with a minimum of colour, agreeableness in listening without the artfulness of the sound typical of the cables realized with synthetic materials, and with the possibility of varyingxe2x80x94according to the requestsxe2x80x94the response to the signal of said cable.
The aim set forth is reached, according to the present invention, by means of a connection cable, that may be calibrated, for the audio signal in recording or reproducing devices, consisting of a plurality of conductors out of gold, copper and silver, connected in parallel, of equal or different sections, with a silk or cotton dielectric, for the insulation of the wires and of the braidings, preferably black, and with connectors out of pure copper.
The advantages of the cables according to the present invention consist in that said black silk or cotton dielectric has the feature of not colouring the sound, as well as the pure copper connector, thus realizing a reproduction with a particularly natural tone-colour, while the parallel connection of connectors of said different metalsxe2x80x94following to the variation in the relationship between the metal quantitiesxe2x80x94allows to obtain a calibrating of the reproduced sound.